In an image forming apparatus such as a copier, toner is supplied from a toner container into a developing unit. When the toner stored in the container is exhausted, the container must be discarded and exchanged with another container storing new toner.
With respect to such toner, a toner manufacturer, from a viewpoint of supply of high-quality images to a user, recommends him to use manufacturer-recommended toner including a manufacturer's genuine article. However, an imitation just like the manufacturer's genuine article is manufactured and it may be on the market. When the toner quality of this imitation is low, the quality of images obtained by use of the toner is low and various troubles may be stirred up easily. Furthermore, a user himself may often consider and use such an imitation as a manufacturer's genuine article. In this case, a user makes a complaint about such a trouble against a manufacturer of genuine toner.
To eliminate such a problem, an art for identifying whether toner is a genuine article of a manufacturer or an imitation has been developed. For example, an art for attaching a bar code to a toner container, reading the bar code information, thereby identifying whether it is a genuine article or not is disclosed in Japanese Patent Application Publication No. 5-224479. Further, in Japanese Patent Application Publication No. 2003-58003, an art for attaching an EEPROM to a toner container, recording an identifying code by user in the EEPROM, reading existence of the user identifying code at the time of use of the toner, and identifying it as an imitation or a genuine article is disclosed.
However, decoding such codes by manufacturers of imitations progresses, and the codes are altered, and imitations of toner are not exterminated actually.
Therefore, a toner identification art by which codes can be hardly decoded is desired. By doing this, it is necessary to prevent beforehand false toner from use.
As described above, conventionally, there is an art for identifying whether a recording material such as toner is a genuine article or not by an identifying code. However, decoding and altering of identifying codes are executed easily.